To evaluate the stress distribution of inlays fabricated with restorative materials of different elastic moduli under two functional loading conditions by using three-dimensional (3D) finite element analysis (FEA) models of a second maxillary premolar.
A 3D model of a sound maxillary left second premolar and its supporting bone was generated in a previous study and reutilized under permission of the authors for the present study. Inlay models obtained from the sound tooth were then assigned according to the type and inherent elastic modulus of the restorative material used, as follows microhybrid composite (Filtek Z250); indirect resin composite (Paradigm); lithium disilicate reinforced glass ceramic (IPS e.max Press); and type III gold alloy. The geometric models were then exported for 3D FEA. All materials were considered isotropic, homogeneous, and linear-elastic. A static load of 100 N was applied in two conditions axially at both cusps (axial loading) and at the mesial marginal ridge (proximal loadine for maxillary premolars restored with inlays in the presence of occlusal contact on the marginal ridge.To evaluate the effect of SARS CoV-2 effective mouthwashes on the color change (ΔE), translucency parameter (TP) and average surface roughness (Ra) of a nanofill resin composite (Filtek Ultimate).
91 composite specimens (10 mm in diameter, 1 mm thickness) were prepared using a stainless-steel mold and randomly divided to seven groups as follows Group 1 (CHX) 0.12% CHX digluconate + 0.15% benzydamine hydrochloride (96% alcohol), Group 2 (HAc) hypochlorous acid (500 ppm), Group 3 (PVP-I) 1% povidone iodine, Group 4 (H2O2) 1.5% hydrogen peroxide, Group 5 (CHX + C) 0.09% chlorhexidine digluconate + cyclodextrin + citrox, Group 6 (CPC) 0.075% cetylpyridinium hydrochloride, Group 7 (Control) artificial saliva. The initial color values were determined by a spectrophotometer on both white and black backgrounds. The specimens were immersed in 20 mL mouthwash for 1 minute with a 12-hour interval. The Ra, ΔE and TP were determined after 1, 2 and 3 weeks. Data were analyzed using repeated measures ANOVA, one-way ANOVA, post-hoc Bonferroni and Tukey tests (P&lt; 0.05).
The highest and the lowest ΔE3 (after 3 weeks) value were observed in H2O2 (1.57± 0.29) and CHX (0.92± 0.17) groups, respectively. The CHX and CPC groups demonstrated significantly lower ΔE3 values than the control group (P&lt; 0.05). CHX, HAc and PVP-I significantly affected the TP (P&lt; 0.05). None of the groups demonstrated any significant changes of Ra scores (P&gt; 0.05).
Within the limitations of this study some of the mouthwashes affected the ΔE and TP of the Filtek Ultimate nanofill resin composite. The Ra was not affected by any of the mouthwashes.
Within the limitations of this study some of the mouthwashes affected the ΔE and TP of the Filtek Ultimate nanofill resin composite. The Ra was not affected by any of the mouthwashes.To assess the prevalence of periapical abscesses (PAs) in individuals with vitamin D deficiency who are not treated and in individuals treated with a vitamin D supplement (calciferol).
Integrated data of hospital patients was used. Data from the corresponding diagnosis codes for periapical abscess and vitamin D deficiency were retrieved by searching the appropriate query in the database. The Risk Ratio (RR) for periapical abscesses, its association with vitamin D deficiency and intake of calciferol were calculated and analyzed statistically.
The RR for prevalence of periapical abscesses in patients with vitamin D deficiency was 3.44. Presence of PAs was significantly higher in patients with vitamin D deficiency compared to patients without vitamin D deficiency (P&lt; 0.0001). The RR and the prevalence of PAs for patients treated with calciferol were significantly lower compared to untreated patients (P&lt; 0.0001).
Dentists should be aware of the possible association between vitamin D deficiency and occurrence of periapical abscesses. It appears that the prevalence of periapical abscesses is higher in patients with vitamin D deficiency. Calciferol supplement may reduce the prevalence of such periapical disease in these patients.
Dentists should be aware of the possible association between vitamin D deficiency and occurrence of periapical abscesses. It appears that the prevalence of periapical abscesses is higher in patients with vitamin D deficiency. Calciferol supplement may reduce the prevalence of such periapical disease in these patients.To evaluate the effect of different substrate stiffness [sound dentin (SD), resin composite core (RC) or metal core (MC)] on the stress distribution of a zirconia posterior three-unit fixed partial denture (FPD).
The abutment teeth (first molar and first premolar) were modeled, containing 1.5 mm of axial reduction, and converging axial walls. A static structural analysis was performed using a finite element method and the maximum principal stress criterion to analyze the fixed partial denture (FPD) and the cement layers of both abutment teeth. The materials were considered isotropic, linear, elastic, homogeneous and with bonded contacts. An axial load (300 N) was applied to the occlusal surface of the second premolar.
The region of the prosthetic connectors showed the highest tensile stress magnitude in the FPD structure depending on the substrate stiffness with different core materials. The highest stress peak was observed with the use of MC (116.4 MPa) compared to RC and SD. https://www.selleckchem.com/products/ch-223191.html For the cement layer, RC showed the highest values in the molar abutment (14.7 MPa) and the highest values for the premolar abutment (14.4 MPa) compared to SD (14.1 and 13.4 MPa) and MC (13.8 and 13.3 MPa). Both metal core and resin composite core produced adequate stress concentration in the zirconia fixed partial denture during the load incidence. However, more flexible substrates, such as composite cores, can increase the tensile stress magnitude on the cement.
The present study shows that the choice of the cast core and metallic post by the resin composite core and fiberglass post did not improve the biomechanical behavior of the FPD. This choice must be performed based on clinical criteria (other) than mechanical.
The present study shows that the choice of the cast core and metallic post by the resin composite core and fiberglass post did not improve the biomechanical behavior of the FPD. This choice must be performed based on clinical criteria (other) than mechanical.